1. Field of the Invention
The present invention relates generally to computer assisted image guided medical and surgical navigation systems that generate images during medical and surgical procedures indicating the relative position of various body parts, surgical implants, and instruments. In particular, the present invention relates to an instrument for use in an image guided surgery navigation system that enables the system to track both the depth and the trajectory of the instrument during surgery.
2. Background of Related Art
Computer assisted image guided medical and surgical navigation systems are known and used to generate images in order to guide a doctor during a surgical procedure. Such systems are disclosed, for example, in U.S. Pat. No. 5,383,454 to Bucholz; PCT application Ser. No. PCT/US94/04530 (Publication No. WO 94/24933) to Bucholz; and PCT application Ser. No. PCT/US95/12984 (Publication No. WO 96/11624) to Bucholz et al., incorporated herein by reference.
In general, these image guided systems use images of a body part, such as CT scans, taken before surgery to generate images on a display, such as a CRT monitor screen, during surgery for representing the position of a surgical instrument with respect to the body part. The systems typically include tracking devices such as, for example, an LED array mounted on a surgical instrument as well as a body part, a digitizer to track in real time the position of the body part and the instrument used during surgery, and a monitor screen to display images representing the body and the position of the instrument relative to the body part as the surgical procedure is performed.
There is a need in the art for a surgically navigable tool for use with these image guided systems that is simple to use and manipulate, that enables the computer tracking system to track both the trajectory of the instrument and the depth that the instrument is inserted into the body, and that is easily interchangeable with alternative drive sources such as a ratcheting handle or other instruments such as awls, taps, and screwdrivers.